In buildings, such as a grocery store, where the ceiling often extends to about 12 feet in height or more, air stratification often occurs in the occupied zone, i.e., the lower regions of the store area immediately above the floor, typically the lower half where shoppers walk the aisles, and the unoccupied zone, i.e., the remaining upper regions of the store area, typically the upper half. Hot stagnant air remains near the ceiling and cool stagnant air remains near the floor in the lower region, usually to the discomfort of shoppers in the store.
This stagnation of cool air especially is apparent in those aisles adjacent refrigerated food displays where the cool air is bothersome to shoppers walking along the aisles in the store. To remove this heavy, cool, stagnant air on the aisles adjacent the refrigerated food displays, most refrigerated food displays in conventional grocery stores are equipped with return air ducts extending beneath the display which draw the cool air from the aisle and into separate plenum chambers and air conditioning apparatus.
The initial installation cost of this equipment having the return air ducts therebeneath is expensive; however, heretofore, installation of this equipment has been necessary. Most ceiling mounted air diffusers cannot induce upwardly the heavy, cool, stagnant air lying in the aisles adjacent the refrigerated food displays. Typically, the discharged air from these diffusers flows along the face of the ceiling in a manner commonly referred to as the coanda effect. The heavy, cool, stagnant air lying in the aisles adjacent the refrigerated food displays could be induced upwardly if the velocity of the air discharged from a diffuser mounted overhead was increased and a jet of air directed into the lower regions of the store in the aisles. Increasing the velocity of air is not readily desired, however, because the high velocity air creates a draft in the aisles of the lower regions of the store, which is discomforting and bothersome to shoppers walking therein.
One type of air diffuser unit has been constructed so that when it is mounted free without a finished ceiling such as in an industrial warehouse or factory, it will provide a rotational, highly turbulent current of air into the upper region of a building while inducing an upward, draft-free flow of air from the lower region of the building. An example of this type of diffuser is found in Belgium Patent No. 886544, Apr. 1, 1981 and Swiss Patent No. 648923, Apr. 15, 1985, and includes a housing with a flared outlet and means defining a tubular air passageway positioned coaxially of the housing and also defining an annular air passageway therebetween. A plurality of vanes are mounted in the annular passageway for producing rotational, highly turbulent currents of air. Means associated with the tubular air passageway controls the volume of air passing therethrough and also controls the flow pattern of air flowing from the annular air passageway so that as the volume of air passing through the tubular air passageway is increased, the flow pattern of the currents of air from the annular passageway is directed downwardly in a more vertical direction over a smaller area of the factory. This prior art diffuser design has been found inadequate in a grocery store environment having a finished ceiling because the air discharged from the diffuser was subject to the coanda effect such that the discharged air flowed along the face of the ceiling and did not induce upwardly the heavy, cool, stagnant air adjacent refrigerated food displays and effect mixing thereof in the upper regions of the store with the conditioned air flowing from the diffuser units and also for mixing with that higher temperature air inherently residing in the upper regions of the store above the shoppers.
It is therefore an object of this invention to provide an air conditioning system for a grocery store or the like having refrigerated food displays or the like along certain aisles of the store and ceiling mounted air outlet diffuser units mounted in the ceiling for providing a downward flow of conditioned air into the store wherein a plurality of the air outlet diffuser units are constructed and positioned in the store so as to provide a downward flow of conditioned air in such a manner that the shoppers moving about the aisles therebelow receive conditioned air substantially free of drafts for aiding in shopper comfort, while heavy, cool, stagnant air lying adjacent the refrigerated food displays and the like is induced upwardly into upper regions of the store above the shoppers for effecting mixing thereof in the upper regions of the store with the conditioned air flowing from the diffuser units and also for mixing with that higher temperature air inherently residing in the upper regions of the store above the shoppers.
It is another object of this invention to provide an air conditioning system for a grocery store or the like having refrigerated food displays or the like along certain aisles of the store and wherein the heavy, cool, stagnant air lying adjacent the refrigerated food displays and the like is induced upwardly into upper regions of the store above the shoppers for effecting mixing thereof with the conditioned air flowing from the diffuser units and also for mixing with that higher temperature air inherently residing in the upper regions of the store above the shoppers, so that only a single air return conduit is necessary for properly accommodating the entire store due to enhanced mixing of the air within the store and the elimination of the stagnant air areas.
It is still another object of the invention to provide an air diffuser adapted for use with a grocery store air conditioning system, wherein the air diffuser unit can be positioned substantially above the aisles adjacent the refrigerated food displays and with the diffuser being so constructed so as to provide a downward flow of conditioned air into the store in such a manner that the shoppers moving about the aisles therebelow receive conditioned air substantially free of drafts for aiding in shopper comfort, while heavy, cool, stagnant air lying adjacent the refrigerated food displays and the like is induced upwardly into upper regions of the store above the shoppers for effecting mixing thereof in the upper regions of the store with the conditioned air flowing from the diffuser units and also for mixing with that higher temperature air inherently residing in the upper regions of the store above the shoppers.